Organoclay-modified high performance epoxy nanocomposites

Organoclay-modified high performance epoxy nanocomposites were synthesized with a direct-mixing method (DMM) or a high-pressure mixing method (HPMM). X-ray diffraction (XRD) results showed that the basal spacing of organoclay particles in the nanocomposites fabricated with the DMM is increased, but that the organoclay is aggregated on the micro-scale in the epoxy resin. These agglomerates of organoclay mainly came from poor dispersion and could be broken down by the HPMM. The mechanical behavior of materials formed by these mixing methods was investigated. The organoclay was found to simultaneously improve both fracture toughness and elastic modulus of the TGDDM-DDS epoxy system without decreasing strength. The nanocomposites formed by the HPMM showed a dramatic improvement in fracture toughness at very low clay loading; that is, K1C and G1C were increased by 1.7 and 3.2 times respectively, at 1.5 phr (about 1 wt%) organoclay loading. Dynamic mechanical analysis results showed that the glass transition temperature (Tg) of all the nanocomposites decreases slightly as the content of clay increases.